Roller cutter with gauge cutting reamer



March 8, 1960 J. B. STEEN ROLLER CUTTER WITH GAUGE CUTTING REAMER 3 Sheets-Sheet 1 Filed Nov. 21, 1956 ll a l March 8, 1960 J. B. STEEN ROLLER CUTTER WITH GAUGE CUTTING REAMER 3 Sheets-Sheet 2 Filed Nov. 21, 1956 March 8, 1960 J.- B. STEEN ROLLER CUTTER WITH GAUGE CUTTING REAMER Filed Nov. 21, 1956 T1 15. 1 v I/ ,J 4/ Z4 7,, 4 4 Ja 6] 55: 586 55 3 Sheets-Sheet 5 cutters each having of teeth to drill the formation at the bottom of the: hole,

2,927,777 ROLLER CUTTER WITH GAUGE CU riN't;

REAMER James B. Steen, Fort Worth, Tex., assignpr to Chicago Pneumatic Tool Company, New York, N.Y., a corporation of New Jersey Application November 21, 1956, Serial No. 623,637 2 Claims. or. 255-347 This invention relates to rotary rock bits for deep well drilling, and particularly to a roller cutter arrangement adapted for drilling in hard and abrasive formations. It has an especial though not exclusive, application to cutters of the cone type which operate on the earth formation with an approximate true rolling action.

The usual cone type rock bit comprises three conical widely spaced circumferential rows of detritus thus dislodged being re- The rows of teeth, with one exceptwo cones, over a path which extends periphery of the bottom of the hole.

The diameter of the cylindrical wall of the hole, there-- fore, is usually determined by the shape and location of the heel row of teeth on each of the cone cutters. As the drilling proceeds, the teeth, of course, wear in a vertical direction and sometimes they wear along the ends which engage the peripheral wall of the hole-so that the teeth fail to maintain the gauge of the hole and the latter diminishes in diameter. arises when drilling in extremely hard and abrasive formations.

Among the objects of this invention are to reduce-the I wear upon the outermost row of teeth; to overcomethe adverse effects of such the wear on the teeth. 7

A further object of the invention is to provide a space, between the outermost row of cutting teeth and theside wall of the hole, for the removal of cuttings. i

In accordance with this invention, the outermost row of teeth on each cutter is spaced from the heel of the cone so that it is not in contact with the side wall of the hole and thus is protected from wearingaction at its outer end. In order to make it possible to leave such space uncut by the teeth, the present invention provides a novel form of cutting surface for reaming the formation immediately surrounding the track formed by the row of teeth. I p

A feature of this invention is a peripheral rim at the heel of each cone which of a liquid flushing fluid or of pres-v are usually arranged in offset rela- 1 This difficulty frequently wear; and to maintain thegauge of the bore hole against loss of diameter irrespective of States Patent tracking relation'with the heel row of Fig. 11 is a fragmentary v of the cutter of Fig. 10 at the heel portion thereof;-

operates in a novel manner, for

crushing the formation at the bottom of the hole in the marginal area while at the same time shaving the side of the hole to maintain gauge. Another feature resides in the location of the peripheral rim above the cutting portions of the teeth, whereby the circumferential rows of teeth drill in advance and the rim engages the earth formation on an oflset step lying above the area drilled by the teeth.

Another feature of the invention resides in an arrangement of hard metal inserted in the peripheral rim and in the heelface of the cone which rubs against the side wall of the hole.

Other objects and features of the present invention will be apparent fromfthe following description taken in conf nection with the accompanying drawings and appended claims. 7 V h In the accompanying drawings, wherein Figs. l-9 illustrate a preferred form of rock bit embodying this invention and Figs. 10-15 show a modification;

Fig. '1 is a fragmentary view of a rock bit showing in I longitudinal section and also showing in of the remaining two cutters;

a preferred form of conical cutter Fig. 2 is a fragmentary end view in elevation of the lowermost Fig. 1; I

Fig. 3 is a fragmentary plan view of the heel portion of the cutter, when viewed transversely of the axis of rotation thereof;

part of the cutter, looking from the left in Fig. 4 is a fragmentary plan view of the tip or apex portion of the cutter when viewed from the line 4 4 inFig. .1, in the direction of the arrows;

Fig. 5 is. an end view of the illustrative cutter with away, looking along the axis of the lower part broken the'cutter from the line 55 in Fig. 1 in the direction of the arrows;

Fig. 6 is a fragmentary longitudinal section taken 1 through the teeth in the .two outermost rows of said cut: showingter as indicated by the arrows 6 in Fig. 3, and also the adjacent portion of the borehole;

Fig. 7 is a view similar to Fig. 6; but taken through the radial grooves between the cutter teeth as indicatedby the arrows 7 in Fig. 3;

Fig. 8 is a view similar to Fig. 6 but on a larger scale and relating to a different cutter, which is shown in dotted lines in Fig. 1;

Fig. 9 is a view similar to Fig. 8 but taken'througlr the radial grooves between the-cutter teeth;

Fig. 10 is a longitudinal section of amodified cutter embodying this invention, portion of the associated spindle and bit head;

development of the bottom Fig. 12 is a fragmentary heel portion of the end view in elevation of the Fig. 13 is a fragmentary longitudinal section of a sec- 0nd cutter designed for use in the same set-as the 'cut--- ter of. Fig. 1;

Fig. 14 is a view similar to Fig. 13 but relating to the Fig. 10 shown in relation shown) extending downwardly and outwardly towardthc side wall 24 of the borehole. Each leg supports, near ts lower end, a spindle 25 which extends downwardly 25 has an axis of:rotatio.u which lies in the same vertical plane as the axis of revand inwardly. Each spindle olution 22 of the drill bit and is spaced ,apart from the vertical plane of the axis of each remaining spindle. The spindle 25 provides a cutter 26. Suitable rolling and friction bearings (not shown) are interposed between the cutter and-the spindle according to the usual well-known. arrangement.

The surface of the conical broken lines the interfitting portions showing also a fragmentary cutter, looking from the left in 3:

taken through the rasupport for a conical roller" cutter .26 comprises a large number of teet-h27 each integral with the body of the 3 cone and inclined toward the apex so as to extend vertically downward when in contact with the bottom of the hole. The teeth are arranged in circumferential. rows 27a, 27b, 27c, 27d; separated by wide and deepcircumferential grooves 28, also in a row of similar teeth 27e in radial alignment with the teeth 27d. The teeth in rows 27a, 27b and 270 are separated by transverse or radial grooves 29. Referring to Fig. 5, each radial groove,

between the teeth 27b or 270 comprises a curved bottom portion 29b and two straight sides 29s diverging from the bottom. A rounded portion 31 connects the straight sides of two adjacent radial grooves and forms the crest portion of the teeth 27. The crest portions are substantially spherical and engage the formation at the bottom of the bore hole with a crushing action to fracture the formation. Below the crest, the tooth has a root portion generallyin the shape of a frustum of a pyramid, which serves to provide deep penetration and'ample space for the removal of cuttings.

The teeth 27a are similar to the teeth 27b and 27c as to the rounded crest portions but are not provided with the pyramidal root portion due to space limitations. As seen in Figs. 1, 4 and 5, the tip portion of the cone cutter immediately in front of row 27a is provided with a dull blade 32 extending diametrically at the apex end of the cone. The blade is positioncd to cut the, center of'the bore hole and thus perform the same function as the usual spear point but is so shaped as to avoid any sharp corners. 27e are in line with each other and form practically a single row of teeth as they are separated by a relatively narrow circumferential groove 33. Radial grooves 34 extend between the teeth 27d and part way through the outermost row 27e. Grooves 34 are similar to the radial grooves 29 but lose depth as they approach the heel of the cone cutter 26.

In accordance with this invention, the teeth 27e are spaced from the heel 35 of the conical cutter, leaving a marginal area 36 between the side wall 24 of the bore hole and the area cut by the outermost row of teeth 272, which area extends as far as the broken line 37 in Figs. 1, 3 and 6. In this respect, the invention departs from the standard practice of placing the outermost circumferential row of teeth at the extreme outer end of the cutter so that they engage the side wall 24 of the hole and maintain the gauge thereof. If that practice were followed in the design of a cone having rounded teeth as here shown, the spherical crests 27 would soon become worn at the point of tangency with the side wall 24 where they scrape againstthe earth formation'and would fail to maintain gauge, thereby causing the hole to lose diameter. This is especially true in thevery hard abrasive formations for which thepresent invention was designed; To overcome that problem, the invention proposes to avoid all contact between the outermost row of teeth 272 and the side wall 24, and rely upon other means to maintain the gauge of the hole, which will be described presently. The narrow annular area 36 provides a space for the reception of cuttings or particles of detritus dislodged under the crushing action of the adjacent teeth 27e. The cuttings are carried to the surface of the hole by the action of liquid or gaseous flushing fluid discharged through. suitable ports 33in the bit head.

In order to cut the marginal area 36 in anetfective manner which provides fast penetration of the bit without loss ofgauge due to the wearing of the cutting element under the abrasive action of the side wall of the hole, the invention provides a peripheral rim 4%). The rim consists of a thin cylindrical surface having a width corresponding to that of the marginal area 36; The outer boundary of the rim is defined by the frusto-conical face 35 at the heel of the cone. The inner boundary of the rim is defined by the base. portions of the teeth 27e and bycthe ends ofqthe. radial grooves: 34 between said teeth as shown best in Figs. 3 and 7. lnthe completed state Referring to Figs. 3 and 5, the teeth 27d and of manufacture of the cutter, the rim is unbroken and continuous over the thin cylindrical surface which extends around the circumference of the cutter; and the frusto-conical face at the heel of the cutter is also continuous and substantially smooth. In the process of manufacture, however, the heel surface 35 is interrupted by cutting radial recesses 42, Figs. 2 and 3, the lower ends of which may penetrate into the rim 40. These recesses are filled with hard facing material 43 such as tungsten carbide. As seen in Fig. 6 the bottom of rim lies adjacent the root portion of the cutting tooth 27e and engages the earth formation along an ofiset step 41 lying considerably above the bottom of the hole as defined by the rounded crests of the teeth. The teeth 27, therefore, drill in advance of the lim 40. The peripheral area 36 at the bottom of the hole is not cut by any of the teeth 27 but is removed by the peripheral rim 40 as will be seen by a comparison between Figs. 6 and 7. In a working embodiment of this invention for a size 8% bit the peripheral rim 40 has a width of about onesixtcenth of an inch. This is suflicient to resist premature wear and sharp enough to shave the side wall of the bore hole as it crushes the earth formation in the marginal area 36 immediately below the rim.

It is apparent, therefore, that the gauge of the hole is cut by the rim 40, which acts as a reamer, and is maintained by the frusto-conical heel portion 35 in rubbing against the side wall 24 of the hole. Since the rim 40 is a continuous cylindrical surface or cutting edge, it does not Wear as quickly as in the case of a row of teeth which engages the earth formation at a series of spaced points. Accordingly, the rim 40 will cut the peripheral area of the bore hole throughout the life of the bit without appreciably losing gauge or diameter of hole as in the usual case where a row of teeth is'relied upon to cut the side wall. The outermost row of teeth 27:: being relieved of the gauge cutting function, will last longer as a result. To further prolong the life of the cutting teeth 27 and peripheral cutting rim 40, the cone surface of the cutter 26 is carburized and heat treated to provide a case-hardened skin 44. Preferably, such carburization is carried to a further degree and to a further depth of case as compared with standard practice. This is due to the shape of the teeth and cutting rim 40 and are devoid of sharp corners that otherwise would inhibit the use of deep case.

Referring again to Fig. 1, the cutter or cone 26, which has been described in detail, cooperates with two mating cutters 45 and 46. The second cutter 45 has circumferential rows of teeth 47a, 47b and 47c, arranged to cut an annular formation on the bottom of the hole closely surrounding the annular areas cut by the teeth 27a, 27b and27c respectively. The teeth 47a, 47b and 47c are similar in shape to the teeth 27b and 27c. Teeth 47a, 47b and 47c extend into the circumferential grooves 28. separating the rows of teeth 27 on cutter 26. Near its heel, cutter 45 is provided with an outer row of teeth 47d arranged to track over the area cut by the row 27e, and also with a hard surfaced heel 48 arranged to cooperate with a rim 50 to cut the formation at the outer edge of the hole. The rows of teeth 47a, b, c, d are separated by circumferential grooves 49 similar in construction and purpose to the grooves 28 in the first cutter. The third cutter 46 is provided with a hard surfaced heel 51, rim 52 and outer row of teeth 53d. Cutter 46 also has circumferential rows of teeth 53a, 53b, 530, similar to the teeth 47a, 47b and 47c, and arranged respectively to an area immediately surrounding the annular area cut by the latter. Teeth 53a and 53b interfit within the grooves 28 and 49 between the rows of teeth on both of the other two cutters, thus providing a self-cleaning action.

Referring to Fig. 8, the row of teeth 47d on the second cutter 45 drills an annular groove or track 55 on the bot tom of the bore hole, which coincides with the track cut by the teeth 27c of the first cutter and the teeth 53d of the third cutter. As stated previously, this track is separated from the wall 24 of the bore hole. The rim 50 engages the earth formation on the oifset step 41 which is higher than the track 55. Rim 50 cooperates with the rims 40 and 52 on the other two cutters to remove the marginal earth formation on step 41 with a combined crushing and shaving action, asappears in-Fig. 9.

Figs. -15 illustrate a modification of this invention in which the marginal rim is applied to a chisel toothed cutter. The cutter 57, as shown in Fig. 10, is provided with circumferential rows of teeth 58a, 58b, 58c and 5&1 separated by circumferential grooves 59. The teeth are inclined toward the apex so as to extend vertically downward when in contact with the bottom of the bore hole. The teeth in each row are divided up by transverse or radial grooves 61. The teeth have crests 62 between the grooves 61 and engage the bottom of the hole along radial lines. The teeth shown in Fig. 10 are conventional except for the fact that the outermost row 58d does not extend all the way to the side wall 24 of the bore hole but is cut short to leave a marginal space 63 uncut by the chisel teeth. The cutter 57 cooperates with a second cutter 64 (Fig. 13) and a third cutter 65 (Fig. 14) each of which has a row of teeth near its heel adapted to track the teeth 58d over an annular area which extends close to the side wall 24 but which is separated therefrom by the marginal area 63. The tracks cut by the three cutters 57, 64 and 65 are shown in Fig. 15. The marginal area 63 is cut by a rim 66 provided on each of the three cutters. As in the case of the first form of invention, the rim 66 is bounded on the outside by the frusto-conical heel 68 and on the inside by the outer ends of the radial grooves 61. Heel 68 may be recessed to receive hard metal 69 as in the case of Fig. 1. As seen in Fig. 15, the rim 66 engages the earth formation along a marginal area which is a step chisel teeth 58d.

While the present invention has been described with reference to a cone cutter having rounded teeth and to a cone cutter having chisel teeth, it is applicable to other shapes of teeth and cutters, for example, cutters used in cross roller bits.

higher than the track cut by the 6 What is claimed is: p I 1. In an earth boring drill, a roller cutteradapted to be supported on a bit head for rotation about an" axis inclining downwardly and inwardly from said bit head, said cutter having at its outer end a frusto-conical heel face abutting the side with the earth formation at the bottom of the hole, the outermost row beingspaced from the frusto-conical heel face at the outer end of the cutter to cut an annular path spaced from the side wall of the bore hole, and reaming means for cutting the earth formation surro'unding the path cut by said outermost row, said reaming means comprising a rim on said cutter consisting of a surface extending continuously around the circumference of the cutter adjacent the frusto-conical heel face and positioned to roll over the bottom of the bore hole, said rim being shorter in radius than the outermost row of teeth whereby the circumferential rows of teeth engage the earth formation in advance of said rim, the bottom of the rim engaging the earth formation on the bottom of the hole with a crushing action along an oifset step lying above the paths cut by the circumferential-rows'of teeth.

2. A roller cutter according to claim 1, in which the teeth in said outermost row are each provided'with a root portion of substantially frusto-pyramid shape and a crest portion of substantially spherical shape, said rim engaging the olfset'step at the level of the root portions of the teeth. 1

References Cited in the file of this patent UNITED STATES PATENTS Canada May 30,

wall of the bore hole, teeth on said cutter arranged in circumferential rows spaced at dilferent distances outwardly from the bit head axis and engageable; 

